What should you know about effects of heat exhaustion?

In hot or humid conditions, sweating removes water and salts while the body struggles to lose heat. This may cause thirst, excessive sweating, headache, dizziness, cramps, tiredness, nausea and cool, clammy skin. Dark urine can suggest that you need more fluid, although urine colour is not a diagnosis. People who are older, pregnant, taking certain medicines or working hard in heat may become unwell more quickly.

Move to a cool or shaded place, stop exertion and loosen unnecessary clothing. Lie down with the legs raised if comfortable, cool the skin with damp cloths or a fan, and take frequent small sips of water or an oral rehydration drink if you are awake and not vomiting. Avoid alcohol. Someone should stay with you and check whether you improve after cooling and drinking.

Call emergency services if the person becomes confused, faints, has a seizure, cannot drink, keeps vomiting, develops very hot skin, or does not improve promptly with cooling. These signs can indicate heat stroke, which needs urgent treatment. Do not give fluids to someone who is drowsy or unable to swallow safely.

Ask how to replace fluids safely, whether a medicine or health condition increases your heat risk, and how to plan rest, shade and drinking during outdoor work or exercise. Discuss repeated episodes even if they settle with cooling.